The present invention relates to fasteners or anchors, and particularly, to fasteners or anchors for securement into medical tissue, particularly bone. The present invention finds particular application in the securement of sutures to bone, particularly for the attachment of torn ligaments or ligament replacements to bone. Although finding particular application in the medical area, the present invention is not limited thereto, and can be applied in other fields, for example, in the construction and general fastener industries.
Various suture anchors and methods of anchoring sutures in body tissue, for example, bone, are known. For example, Hayhurst et al. (U.S. Pat. Nos. 4,041,129 and 5,269,809) disclose a suture anchor having a pivotable toggle end, which upon insertion, is rotated so as to be transverse with respect to an insertion tool. The sutures then extend from the anchor through the aperture provided for the insertion tool. This anchor appears to be difficult to insert, and requires the surgical drilling of two holes, one transverse to the other hole in order to secure the anchor in, for example, hard tissue such as bone. The anchor of these references essentially forms a toggle.
U.S. Pat. Nos. 4,575,295 and 3,053,355 show two fasteners which are secured in premanufactured locking channels by a twisting action. In U.S. Pat. No. 4,575,295, the fasteners are twisted so that tabs of the fasteners underlie flanges of the premanufactured channels. The fastener has grooves therein which lock into downwardly depending tabs of the flanges of the channel. A spring biases the fastener to secure the fastener in the channel.
In U.S. Pat. No. 3,053,355, a curved nut is provided which is inserted into a channel and then twisted. The curved nut has edges which bite into the channel flanges with the edges underlying the flanges of the channel. A bolt is then inserted into the nut to secure another member to the channel.
U.S. Pat. No. 1,091,674 shows a screw fastener which has a blade which is rotated out of the longitudinal direction of the screw once the screw is inserted into a bore to fasten the screw securely into the bore. The blade rotates about an axis perpendicular to the axis of the screw.
U.S. Pat. Nos. 2,077,804 and 2,685,877 show various medical fasteners. In U.S. Pat. No. 2,077,804, the fastener includes two flat transverse members which rotate on an axis perpendicular to the longitudinal direction of the fastener thereby to secure the fastener in position.
U.S. Pat. No. 2,685,877 shows a femoral head prosthesis including two locking keys which individually pivot about an axis perpendicular to the longitudinal axis of the fastener to secure the femoral head prosthesis in position in the femur.
U.S. Pat. Nos. 5,203,787, 5,306,301, 5,403,348 and 4,741,320 show other suture anchors. U.S. Pat. No. 1,269,912 shows another general use clamping bolt.
The prior art thus shows various toggle type anchors or fasteners which are adapted to be received in undercuts or below flanges, and which prevent the anchor, through a toggle of the transverse portion of the anchor, from being pulled out of the bore in which it is disposed.
These various fasteners, whether for the construction industry or the medical field, all suffer from complications, including difficulty of use, the need to cut a transverse hole or undercut perpendicular to the direction of the insertion hole and a lack of adequate securement against forces tending to pull the fasteners out of the bores in which they are disposed. In the case of U.S. Pat. Nos. 2,077,804, 2,685,877 and 1,091,674, these patents all suffer from complications in use due to the need to rotate the securement member about axes perpendicular to the fastener axis.
A particular application in the medical field where there is a need for an improved suture anchor is in the securement of ligaments or ligament replacements to bone, and in particular, the rotator cuff ligaments i.e., the ligaments holding the humerus to the clavicle.